Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 19 recordsLinked to original sources

PubMed2007

Tracheal tube tip displacement during laparoscopy in children*.

The risk of endobronchial intubation during laparoscopy because of displacement of the tip of the tracheal tube is a well known problem in adults. Laparoscopy in children is increasingly performed, but there are no data available regarding the above problem. We prospectively studied 46 children aged 2 months to 15.7 years (median 4.2 years) undergoing laparoscopy. After tracheal intubation with the Microcuff Pediatric Endotracheal Tube, with the 'intubation depth marking' of the tube at the vocal cords, the distance from the tracheal tube tip to the carina was endoscopically measured with the patient in the neutral position and with 20 degrees head-down tilt, both with and without capnoperitoneum. Maximal displacement of the tip of the tracheal tube tip in cm was 0.5+(0.05xage (years)) for 20 degrees head-down tilt, 0.6+(0.09xage (years)) for capnoperitoneum alone, and 1.2+(0.11xage (years)) for 20 degrees head-down tilt with capnoperitoneum. In no patients did endobronchial intubation occur with the tracheal tube placed according to the intubation depth marking.

Adolescent↗

PubMed2006

Evidence-based guidelines for management of attention-deficit/hyperactivity disorder in adolescents in transition to adult services and in adults: recommendations from the British Association for Psychopharmacology.

Attention-deficit/hyperactivity disorder (ADHD) is an established diagnosis in children, associated with a large body of evidence on the benefits of treatment. Adolescents with ADHD are now leaving children's services often with no readily identifiable adult service to support them, which presents problems as local pharmacy regulations often preclude the prescription of stimulant drugs by general practitioners (GPs). In addition, adults with ADHD symptoms are now starting to present to primary care and psychiatry services requesting assessment and treatment. For these reasons, the British Association for Psychopharmacology (BAP) thought it timely to hold a consensus conference to review the body of evidence on childhood ADHD and the growing literature on ADHD in older age groups. Much of this initial guidance on managing ADHD in adolescents in transition and in adults is based on expert opinion derived from childhood evidence. We hope that, by the time these guidelines are updated, much evidence will be available to address the many directions for future research that are detailed here.

Adolescent↗

PubMed2006

Clinical evaluation of cuff and tube tip position in a newly designed paediatric preformed oral cuffed tracheal tube.

BACKGROUND: To assess the adequacy of the position of the tracheal tube cuff and tracheal tube tip in the recently introduced preformed oral Microcuff paediatric endotracheal tube (PET) using the manufacturers recommendations for Microcuff tracheal tube size selection. METHODS: With Hospital Ethics Committee approval and informed parental consent, the tracheas of children from birth to adolescence were orally intubated with the preformed oral Microcuff PET. First, the position of the tracheal tube's intubation depth mark in relation to the vocal cords was assessed. Second, the distance 'tracheal tube tip-to-carina' was endoscopically measured with the patient supine and the head in a neutral position and the tube placed with the centre mark at the lower incisors or alveolar ridge. RESULTS: A total of 166 children aged from 0.1 to 16.4 yr (median 5.9 yr) were studied. In five patients the intubation depth mark was above (5 mm each), in 22 patients at the level of and in the remaining 139 patients below the vocal cords. No endobronchial intubation occurred. In four patients the distance 'tracheal tube tip-to-carina' was smaller than the safety margin to prevent endobronchial intubation during head-neck flexion. CONCLUSION: The new oral preformed cuffed tracheal tubes allow safe placement in almost all patients when inserted according to the tube bend. The critically low tube tip and the high cuff positions in a few tubes when placed according to the tube bend requires clinical alertness.

Adolescent↗

PubMed2006

Bulk fluorescence measurements cannot probe the survival-time distribution of single molecules.

Using a straightforward theoretical approach, we show that an ensemble of dyes with a simple first-order photobleaching kinetics yields a power-law decaying emission intensity in a heterogeneous excitation field in bulk fluorescence experiments. Our theoretical considerations are experimentally confirmed for two distinct classes of small organic fluorophores represented by the classical laser dye rhodamine-6G on glass in air and the cyanine dye DiI(C18) in a thin polymethylmethacrylate film. Our results provide evidence that the time course of bleaching in a bulk sample in general does not allow derivation of the properties of survival times of individual quantum systems.

Journal Article↗

PubMed2006

[Takayasu's arteritis without manifest arterial stenoses as a cause of fever of unknown origin].

HISTORY AND CLINICAL FINDINGS: Two women, aged 59 and 53 years, presented with a history of several months of classical fever of unknown origin (FUO), largely normal physical findings, and elevated markers of systemic inflammation. INVESTIGATIONS: After initially unremarkable findings, duplex-sonography detected circular, hypoechogenic wall thickening of the axillary arteries without hemodynamically significant narrowing of the lumen. 18F-fluorodeoxyglucose positrone emission-tomography (18F-FDG-PET) revealed marked vascular tracer uptake in the aorta and in the proximal arteries of the arms and legs. TREATMENT AND FOLLOW-UP: The diagnosis of Takayasu's arteritis was made, and high-dose prednisone treatment was initiated. Within a few days both patients became asymptomatic. CONCLUSIONS: Large vessel vasculitis is a known cause of FUO. Duplex-sonography and 18F-FDG-PET are able to detect these disorders at an early stage before the onset of clinically relevant arterial obstructions. More widespread use of these techniques may show that large-vessel vasculitis is more common than previously thought.

Arterial Occlusive Diseases↗

PubMed2006

The basal ganglia are hyperactive during the discrimination of tactile stimuli in writer's cramp.

Writer's cramp is a focal hand dystonia that specifically affects handwriting. Though writer's cramp has been attributed to a dysfunction of the basal ganglia, the role of the basal ganglia in the pathogenesis of writer's cramp remains to be determined. Seventeen patients with writer's cramp (nine females; age range: 24-71 years) and 17 healthy individuals (six females; age range: 27-68 years) underwent functional MRI (fMRI) while they discriminated the orientation of gratings delivered to the tip of the right index finger. Statistical parametric mapping was used to analyse the fMRI data. The significance level was set at a corrected P-value of 0.05. Relative to healthy controls, patients with writer's cramp showed a widespread bilateral increase in task-related activity in the putamen, caudate nucleus, internal globus pallidus and lateral thalamus. In these areas, hyperactivity was more pronounced in patients who had recently developed writer's cramp. The enhanced response of the basal ganglia to tactile input from the affected hand is compatible with the concept of impaired centre-surround inhibition within the basal ganglia-thalamic circuit and may lead to an excessive activation of sensorimotor cortical areas during skilled movements affected by dystonia. Outside the basal ganglia, dystonic patients showed task-related overactivity in visual cortical areas, left anterior insula and right intraparietal sulcus, but not in the primary or secondary sensory cortex. In addition, task-related activity in the cerebellar nuclei, posterior vermis, right paramedian cerebellar hemisphere and dorsal pons was inversely related with the severity of hand dystonia. Regional activity in these areas may reflect secondary adaptive reorganization at the systems level to compensate for the dysfunction in the basal ganglia-thalamic loop.

Adult↗

PubMed2006

[Pulmonary microscopic tumor embolism syndrome].

HISTORY: A 76-year-old woman and a 62-year-old man were both referred to our clinic because of an unexplained weight loss, increasing dry cough and shortness of breath. INVESTIGATIONS: Investigations revealed an adenocarcinoma of the colon with retroperitoneal, mediastinal and supraclavicular lymph node metastasis and poorly differentiated carcinoma of the prostate with extensive bone metastases. During their hospital stay both patients developed increasing shortness of breath and clinical signs of right heart failure. Echocardiography confirmed severe pulmonary hypertension and dilatation of the right ventricle in both patients. Despite the high degree of clinical suspicion CT scans of the thorax could not demonstrate pulmonary embolism. DIAGNOSIS, TREATMENT AND COURSE: During the following days the patients condition deteriorated further and both patients' died from irreversible right heart failure. Both autopsies showed extensive metastatic adenocarcinoma with marked angiosis carcinomatosa of the lungs with numerous occlusions of small arteries and arterioles and resulting cor pulmonale. Thrombotic pulmonary embolism could not be detected. CONCLUSION: In patients with malignant neoplasms, especially adenocarcinomas, dyspnea and signs of increasing pulmonary artery pressure, the possibility of a microscopic pulmonary tumor embolism should be considered after exclusion of more usual causes especially thrombotic pulmonary embolism. In selected cases a cytologic examination of blood aspirated from a wedged pulmonary artery catheter can be performed to prove angiosis is carcinomatosa.

Adenocarcinoma↗

PubMed2006

Tracheal tube-tip displacement in children during head-neck movement--a radiological assessment.

BACKGROUND: Aims of this study were to assess the maximum displacement of tracheal tube tip during head-neck movement in children, and to evaluate the appropriateness of the intubation depth marks on the Microcuff Paediatric Endotracheal Tube regarding the risk of inadvertent extubation and endobronchial intubation. METHODS: We studied children, aged from birth to adolescence, undergoing cardiac catheterization. The patients' tracheas were orally intubated and the tracheal tubes positioned with the intubation depth mark at the level of the vocal cords. The tracheal tube tip-to-carina distances were fluoroscopically assessed with the patient supine and the head-neck in 30 degrees flexion, 0 degrees neutral position and 30 degrees extension. RESULTS: One hundred children aged between 0.02 and 16.4 yr (median 5.1 yr) were studied. Maximum tracheal tube-tip displacement after head-neck 30 degrees extension and 30 degrees flexion demonstrated a linear relationship to age [maximal upward tube movement (mm)=0 0.71 x age (yr)+9.9 (R(2)=0.893); maximal downward tube movement (mm)=0.83 x age (yr)+9.3 (R(2)=0.949)]. Maximal tracheal tube-tip downward displacement because of head-neck flexion was more pronounced than upward displacement because of head-neck extension. CONCLUSIONS: The intubation depth marks were appropriate to avoid inadvertent tracheal extubation and endobronchial intubation during head-neck movement in all patients. However, during head-neck extension the tracheal tube cuff may become positioned in the subglottic region and should be re-adjusted when the patient remains in this position for a longer time.

Adolescent↗

PubMed2006

[Intravenous midazolam-ketamine anaesthesia for closed reduction of forearm fractures in children: impact of additional axillary plexus anaesthesia].

BACKGROUND: The aim of this study was to compare ketamine requirements in children undergoing closed reduction of forearm fractures under midazolam-ketamine anaesthesia with or without axillary plexus anaesthesia. METHODS: With hospital ethical committee approval, we retrospectively analyzed the records of children who received midazolam-ketamine anaesthesia in the years 2000-2001 (group A) and midazolam-ketamine anaesthesia combined with axillary plexus anaesthesia in the years 2002-2004 (group B) for closed reduction of forearm fractures. Requirements for ketamine and postoperative analgesics were noted. Groups were compared with the Mann-Whitney U-test or T-test and the chi2-test (p<0.05). RESULTS: A total of 455 children (group A 225/group B 230) were included in this study. The total amounts of ketamine were not statistically different between the two groups (p=0.154). However, ketamine requirements became less if the time interval between start of axillary plexus anaesthesia and start of intervention became more than 15 min (p<0.05). Patients in group B requested fewer analgesics in the postoperative period (p<0.01). CONCLUSIONS: In the clinical routine of an emergency department the combination of midazolam-ketamine anaesthesia with axillary plexus anesthesia for closed reduction of forearm fractures in children did not result in lower requirements of ketamine.

Adolescent↗

PubMed2006

Does perioperative administration of rofecoxib improve analgesia after spine, breast and orthopaedic surgery?

BACKGROUND AND OBJECTIVE: Data on the effectiveness of cyclooxygenase 2 inhibitors in postoperative pain therapy vary widely. We tested in a prospective, placebo-controlled, randomized, double-blind trial the hypotheses that perioperative (i.e. preoperative and postoperative) administration of the cyclooxygenase 2 inhibitor rofecoxib decreases pain scores and morphine consumption after spine, breast and orthopaedic surgery. METHODS: Five hundred and forty patients scheduled for spine, breast or orthopaedic surgery were randomly assigned to receive in combination with postoperative morphine via patient controlled analgesia pump for 4 days either rofecoxib 50 mg administered perioperatively, rofecoxib 50 mg administered only postoperatively, or placebo. Primary outcome criteria were pain score at rest (numeric rating scale 0-4) and morphine consumption. RESULTS: Perioperative rofecoxib significantly decreased pain score 0 (0-1) vs. 1 (0-2) (median (interquartile range)), and morphine consumption 18 (6-33) vs. 22.5 (12-38) compared with placebo. In contrast, rofecoxib when administered only postoperatively did not significantly improve analgesic effects or side-effects at time of assessment of the main criteria (24 h after skin closure), but during the follow-up period at 48 h and 72 h after skin closure pain scores and morphine consumption were improved compared to placebo. The analgesic effects of rofecoxib were independent from the type of surgery. CONCLUSIONS: Perioperative administration of the cyclooxygenase 2 inhibitor rofecoxib decreases pain scores and morphine consumption after orthopaedic, breast and spine surgery. However, the benefit of preoperative administration of the cyclooxygenase 2 inhibitor seems to be only moderate, suggesting that early postoperative administration may be a useful alternative approach. There is no evidence that the type of surgery influences analgesic effects of cyclooxygenase 2 inhibitors.

Adolescent↗

PubMed2006

Clinically relevant tracheomalacia after repair of esophageal atresia: the role of minimal intra-operative dissection and timing for aortopexy.

BACKGROUND: Tracheomalacia is associated with esophageal atresia (EA), but may go unnoticed from external splinting forces. Intra-operative dissection with fistula division releases external splinting, revealing tracheomalacia only post-operatively. Analysis of surgical technique may disclose an iatrogenic etiology. METHODS: From 1995 - 2004, 44 neonates underwent surgery for EA. All patients underwent pre-, intra- and postoperative bronchoscopy. Operative and bronchoscopic notes were studied for malacia, and extensive dissection of the esophagus and fistula from the trachea. RESULTS: Surgical mortality was 6.8 %. Pre-operative tracheomalacia was diagnosed in 3 patients, who eventually fared well. In 17 other patients, the pre-operative bronchoscopy was negative, but airway obstruction developed post-operatively. Tracheomalacia was documented at the site of the former fistula and surgical release maneuvers. Aortopexy was required in 5 instances, whereas 12 others with malacia were managed conservatively. CONCLUSIONS: Mediastinal connective tissue and the fistula may splint open the marginally diseased airway in patients with EA, the lack of which may disclose previously unknown tracheomalacia after repair. When aggressive release maneuvers have been required, early aortopexy may be preferred to ventilator dependency.

Airway Obstruction↗

PubMed2006

An in vitro study of the compliance of paediatric tracheal tube cuffs and tracheal wall pressure.

Cuff volume-pressure curves and cuff pressure-tracheal wall pressure relationships were investigated in eight brands of currently available cuffed, paediatric tracheal tubes with internal diameters of 5.0 mm. Cuff volume-pressure curves were measured with the cuff unrestricted and with the cuff placed within a tracheal model with wall pressure measurements. With the tracheal tube cuffs, unrestricted cuff compliance at 20 cmH(2)O cuff pressure varied between 0.06 and 0.3 ml x cmH(2)O(-1). With the cuff restricted within the model trachea, all tracheal tube cuffs became considerably less compliant (0.01-0.09 ml x cmH(2)O(-1)). We found tracheal wall pressure was similar to the cuff pressure as long as the resulting cuff diameter was sufficiently large freely to drape the inner tracheal wall. We found that, regardless of whether a higher or lower compliant tube cuff was used, cuff hyperinflation uniformly resulted in potentially compromised tracheal mucosal blood flow; cuff pressure monitoring using cuff pressure limitation is therefore strongly recommended.

Child↗

PubMed2006

Comparison of tracheal tube cuff diameters with internal transverse diameters of the trachea in children.

BACKGROUND: In this study, we evaluated the ratio of the cuff diameters of the Microcuff paediatric tracheal tube (Microcuff PET, Weinheim, Germany) to fluoroscopically measured internal transverse tracheal diameters in children from birth to adolescence. METHODS: With Institutional Ethics Committee approval and parental consent, we measured the internal transverse tracheal diameters from fluoroscopy images in children undergoing cardiac catheterization requiring general anaesthesia with oro-tracheal intubation. Minimal tracheal sealing pressures were assessed at standardized respirator settings. Internal transverse tracheal diameters were compared with cuff diameters at 20 cmH2O cuff pressure. Linear regression analysis was employed to assess the correlation of tracheal diameters with age, height and weight, and to assess the correlation of the cuff/tracheal diameter ratio with sealing pressures. For all tests, P < 0.05 was considered to be statistically significant. RESULTS: One hundred and forty-five patients were studied (62 girls; 83 boys). Transverse tracheal diameters correlated well with age (r = 0.890; P < 0.0001), height (r = 0.900; P < 0.0001) and weight (r = 0.882; P < 0.0001). Tracheal sealing pressures ranged from 4 to 18 cmH2O. The ratio of the tracheal tube cuff diameter to the internal transverse tracheal diameter ranged from 1.06 in tubes with internal diameters of 6.0 and 4.5 mm to 2.01 in a tube with an internal diameter of 3.5 mm (median, 1.43), and did not correlate with tracheal sealing pressures (r = 0.021, P = 0.7999). CONCLUSIONS: The residual diameters of the Microcuff paediatric tracheal tube cuffs were sufficient to cover the measured internal transverse tracheal diameters of children from birth to adolescence. This allowed the internal tracheal mucosal surface to be draped and the trachea to be sealed at very low cuff pressures.

Adolescent↗

PubMed2006

Evaluation of a new recommendation for improved cuffed tracheal tube size selection in infants and small children.

BACKGROUND: The purpose of this study was to evaluate a new recommendation for tracheal tube size selection using second-generation Microcuff paediatric endotracheal tubes (PETs) with optimized outer diameter (OD) of the distal tube. METHODS: With Ethics Committee approval, patients aged from birth to 5 years, requiring general anaesthesia with orotracheal intubation, were included. Tracheal tube sizes were selected as follows: internal diameter (ID) 3.0 mm, birth (if > or =3 kg) to <6 months; ID 3.5 mm, 6 to <18 months; ID 4.0 mm, 18 months to <3 years; ID 4.5 mm, 3 to <5 years. Tracheal tubes with the cuff not inflated were classified as too large if no air leak was obtained at an airway pressure of < or =20 cmH2O. Post-intubation stridor requiring therapy was noted. RESULTS: Three hundred and fifty children were studied. Nine tracheal tubes (2.6%) were too large and had to be exchanged: in patients requiring tracheal tubes of ID 3.0 mm and 3.5 mm, three and four tracheal tubes, respectively, and, in patients requiring tracheal tubes of ID 4.0 mm and 4.5 mm, one tracheal tube in each group. In three patients (0.9%), post-intubation stridor occurred which required therapy. CONCLUSION: The new recommendation presented for the use of second-generation Microcuff PETs with improved OD to ID ratio allows the selection of cuffed tracheal tubes with larger IDs than previously recommended for small children without increased need for tracheal tube exchange or increased incidence of post-intubation stridor in these age groups.

Age Factors↗

PubMed2006

The criterion validity of the Geriatric Depression Scale: a systematic review.

OBJECTIVE: The objective was to provide a systematic review of the screening accuracy of both versions of the Geriatric Depressions Scale (GDS-30, GDS-15). METHOD: An electronic search was performed by using Medline, Embase, Cinahl, Psyndex and the Cochrane library. The selection and examination of papers were performed by two reviewers independently. RESULTS: Among the 42 papers included, important methodological aspects such as sampling methods or blinding of research workers often were not reported. For both GDS versions, similar validity indices were found (GDS-30: sensitivity 0.753, specificity 0.770; GDS-15: sensitivity 0.805, specificity 0.750). Using comparative studies based on the identical samples, both GDS versions showed significantly better validity indices than the 'Yale-1-question' screen, but were similar to the 'Center for Epidemiological Studies Depression scale' (CES-D). CONCLUSION: The GDS does not show a better criterion validity than the CES-D, but methodological limitations of primary studies hamper the generalizability of pooled analyses.

Aged↗

PubMed2006

Cholesterol atheroembolic disease in kidney allografts--case report and review of the literature.

Cholesterol atheroembolic renal disease is a rare cause of renal allograft dysfunction. Two recipients of cadaveric kidney transplantats from the same donor are discussed with presumed graft failure due to cholesterol emboli of donor origin. A review of the literature summarizes the reported cases in renal transplant recipients. While cholesterol embolization of presumed donor origin seems to have a poor renal outcome, cholesterol emboli originating in the recipient have a more favorable prognosis. As donors and recipients of increasing age or prominent atherosclerosis are accepted for transplantation, cholesterol atheroembolic renal disease may become more prevalent and should be considered in patients with renal allograft dysfunction.

Aged↗

PubMed2005

Potential activity of paclitaxel, vinorelbine and gemcitabine in anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma (ATC) has a rapidly fatal course in the mostly elderly patients with a median survival after diagnosis of 4-12 months. Activity of commonly used chemotherapy (doxorubicin) is low, thus more active compounds need to be introduced into the therapeutic concept of ATC. Recently, based on preclinical data Ain et al. conducted a clinical phase II study with paclitaxel 96 h infusion in ATC achieving a promising response rate of 53%. To further improve therapeutic options in ATC, we evaluated the activity of topotecan, oxaliplatin, vinorelbine, gemcitabine and paclitaxel in comparision to cisplatin and doxorubicin (1 and 96 h drug exposure) alone or in combination in the ATC cell lines SW1736 and 8505C. IC50 values were determined by the sulforhodamine B assay, potential clinical activity was estimated by relative antitumor activity (RAA) and drug interaction was analyzed using a parametric response surface approach (Greco model) of the Loewe additivity. Duration of drug effect was estimated by regrowth kinetics. We found paclitaxel, vinorelbine and gemcitabine active in ATC with RAA (1 h drug exposure) ranging from 86 to 454, 15 to 17 and 31 to 140, respectively. The activity of doxorubicin and cisplatin was moderate with RAA ranging from 1.4 to 2.2 and 0.2 to 0.3, respectively. Combined drug exposure of gemcitabine/paclitaxel and gemcitabine/vinorelbine was synergistic with a Loewe index > 0. However, these results did not reach statistical significance with p > 0.05. At clinically relevant drug concentrations paclitaxel, gemcitabine and vinorelbine but not oxaliplatin exerted a sustained growth inhibition after cessation of drug exposure for the complete assay time of 15 days. In conclusion, paclitaxel, gemcitabine and vinorelbine but not topotecan or oxaliplatin appeared to be active in anaplastic thyroid carcinoma based on RAA or growth delay at clinically relevant drug concentrations. Combinations of vinorelbine/gemcitabine and paclitaxel/gemcitabine exerted a trend to synergy. Thus, further evaluation of paclitaxel, vinorelbine and gemcitabine alone or in combination with ATC seems warranted.

Antineoplastic Agents↗

PubMed2005

Characterization of the elastic properties of the nuclear envelope.

Underlying the nuclear envelope (NE) of most eukaryotic cells is the nuclear lamina, a meshwork consisting largely of coiled-coil nuclear intermediate filament proteins that play a critical role in nuclear organization and gene expression, and are vital for the structural stability of the NE/nucleus. By confocal microscopy and micromanipulation of the NE in living cells and isolated nuclei, we show that the NE undergoes deformations without large-scale rupture and maintains structural stability when exposed to mechanical stress. In conjunction with image analysis, we have developed theory for a two-dimensional elastic material to quantify NE elastic behaviour. We show that the NE is elastic and exhibits characteristics of a continuous two-dimensional solid, including connections between lamins and the embedded nuclear pore complexes. Correlating models of NE lateral organization to the experimental findings indicates a heterogeneous lateral distribution of NE components on a mesoscopic scale.

Elasticity↗